Revex

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Revex

Please Note: This Brand Name drug is no longer available in the US.(Generic versions may still be available.)

Warnings

Precautions

WARNINGS

Use of REVEX in Emergencies

REVEX, like all drugs in this class, is not the primary treatment for ventilatory failure. In most emergency settings, treatment with REVEX should follow, not precede, the establishment of a patent airway, ventilatory assistance, administration of oxygen, and establishment of circulatory access.

Risk of Recurrent Respiratory Depression

Accidental overdose with long acting opioids [such as methadone and levo-alpha-acetylmethadol (LAAM)] may result in prolonged respiratory depression. Respiratory depression in both the postoperative and overdose setting may be complex and involve the effects of anesthetic agents, neuromuscular blockers, and other drugs. While REVEX has a longer duration of action than naloxone in fully reversing doses, the physician should be aware that a recurrence of respiratory depression is possible, even after an apparently adequate initial response to REVEX treatment.

Patients treated with REVEX should be observed until, in the opinion of
the physician, there is no reasonable risk of recurrent respiratory depression.

Although REVEX has been used safely in patients with pre-existing cardiac disease,
all drugs of this class should be used with caution in patients at high cardiovascular
risk or who have received potentially cardiotoxic drugs. (See DOSAGE AND
ADMINISTRATION.)

Risk of Precipitated Withdrawal

REVEX, like other opioid antagonists, is known to produce acute withdrawal
symptoms and, therefore, should be used with extreme caution in patients with
known physical dependence on opioids or following surgery involving high doses
of opioids. Imprudent use or excessive doses of opioid antagonists in the postoperative
setting has been associated with hypertension, tachycardia, and excessive mortality
in patients at high risk for cardiovascular complications.

Incomplete Reversal of Buprenorphine

Preclinical studies have shown that nalmefene at doses up to 10 mg/kg (437
times the maximum recommended human dose) produced incomplete reversal of buprenorphine-induced
analgesia in animal models. This appears to be a consequence of a high affinity
and slow displacement of buprenorphine from the opioid receptors. Hence, REVEX
may not completely reverse buprenorphine-induced respiratory depression.

Carcinogenesis and Mutagenesis and Impairment of Fertility

Nalmefene did not have mutagenic activity in the Ames test with five bacterial
strains or the mouse lymphoma assay. Clastogenic activity was not observed in
the mouse micronucleus test or in the cytogenic bone marrow assay in rats. However,
nalmefene did exhibit a weak but significant clastogenic activity in the human
lymphocyte metaphase assay in the absence but not in the presence of exogenous
metabolic activation. Oral administration of nalmefene up to 1200 mg/m2/day
did not affect fertility, reproductive performance, and offspring survival in
rats.

Use in Pregnancy

Pregnancy Category B

Reproduction studies have been performed in rats (up to 1200 mg/m2/day)
and rabbits (up to 2400 mg/m2/day) by oral administration of nalmefene
and in rabbits by intravenous administration up to 96 mg/m2/day (114
times the human dose). There was no evidence of impaired fertility or harm to
the fetus. There are, however, no adequate and well-controlled studies in pregnant
women. Because animal reproduction studies are not always predictive of human
response, this drug should be used during pregnancy only if clearly needed.

Nursing Mothers

Nalmefene and its metabolites were secreted into rat milk, reaching concentrations approximately three times those in plasma at one hour and decreasing to about half the corresponding plasma concentrations by 24 hours following bolus administration. As no clinical information is available, caution should be exercised when REVEX is administered to a nursing woman.

Use in Pediatric Patients

Safety and effectiveness of REVEX in pediatric patients have not been established.

Use in Neonates

The safety and effectiveness of REVEX in neonates have not been established
in clinical studies. In a preclinical study, nalmefene was administered by subcutaneous
injection to rat pups at doses up to 205 mg/m2/day throughout maternal
lactation without producing adverse effects. A preclinical study evaluating
the irritancy of the dosage form following arterial and venous administration
in animals showed no vascular irritancy.

REVEX (nalmefene hydrochloride injection) should only be used in the resuscitation of the newborn when, in the opinion of the treating physician, the expected benefits outweigh the risks.

Geriatric Use

Clinical studies of REVEX (nalmefene hydrochloride injection) did not include sufficient number of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.

Last reviewed on RxList: 6/11/2012
This monograph has been modified to include the generic and brand name in many instances.